EVOLUTIONARY CONSERVATION AND FUNCTIONAL DIVERGENCE OF GLUTATHIONE PEROXIDASE (GPX) GENES IN GALLIFORM BIRDS: GALLUS GALLUS, MELEAGRIS GALLOPAVO, AND COTURNIX JAPONICA

The glutathione peroxidase (GPX) gene family plays a crucial role in maintaining cellular redox homeostasis and protecting against oxidative stress. In this study, we performed a comprehensive comparative analysis of GPX genes in three galliform species: Gallus gallus (chicken), Meleagris gallopavo (turkey), and Coturnix japonica (Japanese quail). Genomic structure, chromosomal localization, phylogenetic relationships, conserved motifs, subcellular localization, synteny, and selection pressure analyses were conducted to investigate the evolutionary conservation and functional divergence of the GPX family. Our findings revealed strong conservation of gene structure and chromosomal positioning, particularly for GPX1, GPX2, GPX3, and GPX7, as well as species-specific expansions and alternative splicing events in genes such as GPX4 and GPX8. Phylogenetic and Ka/Ks analyses indicated that most GPX genes are under purifying selection, with notable instances of positive selection suggesting adaptive functional divergence. Conserved motifs and subcellular localization patterns further supported the core redox-protective roles of GPX proteins, while highlighting their compartment-specific and extracellular functions. Overall, this study enhances our understanding of the evolutionary and functional landscape of the GPX gene family in birds and provides a foundation for future research into avian oxidative stress adaptation and redox signaling.